<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        let a;
        let b, c, d;
        let e = 100;
        let f = "abc", h = [];

        //1.不能重复声明
        // let star = "罗志祥";
        // let star = "小猪";

        //2.块级作用域  全局，函数，eval
        //if else while for {}都是块级作用域
        // {
        //     //块级作用域
        //     let girl = "周扬青"
        // }
        // console.log(girl); //提示girl为定义

        //3.不存在变量提升
        // console.log(song);
        // let song = '青花瓷' //报错

        //4.不影响作用域链
        {
            let school = "财大"
            function fn() {
                console.log(school);
            }
            fn()
        }
    </script>
</body>

</html>